1. Field of the Invention
The present disclosure relates to a Liquid Crystal Display (LCD) device, and more particularly, an LCD device and a driving method thereof, which save the manufacturing cost that is expended by the application of four-color (RGBW) sub-pixels, and enhance an aperture ratio and brightness, thus increasing display quality.
2. Discussion of the Related Art
In LCD devices, manufacturing technology has been advanced, drivability of a driving means is good, low power is consumed, high quality is realized, and a large screen is realized. Therefore, LCD devices are being popularized, and application fields for LCD devices are continuously expanding.
FIG. 1 is a diagram illustrating a pixel structure, which includes RGB sub-pixels of a related art LCD device. FIG. 1 illustrates one unit pixel 10 of a plurality of pixels that are formed in a matrix type, in a liquid crystal panel. Hereinafter, the unit pixel is referred to as a pixel.
Referring to FIG. 1, in a related art LCD device, the one pixel 10 is configured with three-color sub-pixels, namely, a red (R) sub-pixel 12, a green (G) sub-pixel 14 and a blue (B) sub-pixel 16. The LCD device adjusts the transmittance of light, irradiated from a backlight unit onto each sub-pixel, to display a color image.
In the related art LCD device, light emitted from a light source of the backlight unit is transmitted through RGB color filters that are formed at an upper substrate, whereby brightness is degraded. The degradation of brightness is a main cause that degrades the display quality of an image.
FIG. 2 is a diagram illustrating a pixel structure, which includes RGBW sub-pixels of a related art LCD device. FIG. 3 is a diagram illustrating an RGBW quad pixel structure of a related art LCD device.
Referring to FIG. 2, a pixel structure 20 including RGBW sub-pixels further includes a white (W) sub-pixel 28, in addition to the R sub-pixel 22, G sub-pixel 24 and B sub-pixel 26. The pixel structure 20 has been proposed for solving the limitation of the pixel structure of FIG. 1 where brightness is degraded.
Furthermore, as illustrated in FIG. 3, a quad pixel structure 30 which includes RGBW sub-pixels has been proposed, and further includes a W sub-pixel 30, in addition to the existing R sub-pixel 32, G sub-pixel 34 and B sub-pixel 36. In the quad pixel structure 30, the four-color sub-pixels 32, 34, 36 and 38 are arranged in a quad structure.
In the related art LCD device having the pixel structure 20 of FIG. 2 or the quad pixel structure 30 of FIG. 3, the W sub-pixel 28 or 38 increases brightness of light emitted from each pixel.
The brightness has been increased by applying the pixel structure 20 or the quad pixel structure 30. However, the purity of RGB colors becomes lower, causing pure color darkness.
Moreover, a Thin Film Transistor (TFT) is formed in each of four sub-pixels R, G, B and W, and consequently, an aperture ratio of each pixel is reduced.
In the pixel structure 20 of FIG. 2, a data line is additionally formed for supplying image data (data voltage) to the additionally disposed W sub-pixel, causing the reduction in an aperture ratio. Also, as the number of data lines increases, the number of source drive ICs (D-ICs) increases, and thus, the manufacturing cost increases.
In the quad pixel structure 30 of FIG. 3, a gate line is additionally formed compared to the existing stripe pixel structure, causing the reduction in an aperture ratio. Also, the number of gate drive ICs (G-ICs) increases in proportion to the increased number of gate lines, and thus, the manufacturing cost increases.
In regard to a manufacturing process, in the pixel structure 20 of FIG. 2, a TFT mask design structure for the existing three-color (RGB) pixel structure is applied to a process of manufacturing a lower substrate as-is.
However, a process of manufacturing an upper substrate additionally requires a mask for forming the W sub-pixel. Due to this reason, a manufacturing process design is changed, and thus, the manufacturing cost increases.
FIG. 4 is a diagram illustrating image data (data voltages) applied to a pixel structure which includes RGBW sub-pixels of a related art LCD device.
Referring to FIG. 4, when image data (data voltages) are respectively supplied to RGBW sub-pixels by 1-dot inversion scheme, image data having the same polarity are respectively supplied to sub-pixels of the same color that are disposed on one horizontal line. Due to this reason, sub-pixels are deteriorated and crosstalk occurs, causing the degradation of display quality.